'\" t
.\"     Title: CREATE EXTENSION
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 2011-12-01
.\"    Manual: PostgreSQL 9.1.2 Documentation
.\"    Source: PostgreSQL 9.1.2
.\"  Language: English
.\"
.TH "CREATE EXTENSION" "7" "2011-12-01" "PostgreSQL 9.1.2" "PostgreSQL 9.1.2 Documentation"
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.SH "NAME"
CREATE_EXTENSION \- install an extension
.\" CREATE EXTENSION
.SH "SYNOPSIS"
.sp
.nf
CREATE EXTENSION [ IF NOT EXISTS ] \fIextension_name\fR
    [ WITH ] [ SCHEMA \fIschema\fR ]
             [ VERSION \fIversion\fR ]
             [ FROM \fIold_version\fR ]
.fi
.SH "DESCRIPTION"
.PP

CREATE EXTENSION
loads a new extension into the current database\&. There must not be an extension of the same name already loaded\&.
.PP
Loading an extension essentially amounts to running the extension\*(Aqs script file\&. The script will typically create new
SQL
objects such as functions, data types, operators and index support methods\&.
CREATE EXTENSION
additionally records the identities of all the created objects, so that they can be dropped again if
DROP EXTENSION
is issued\&.
.PP
Loading an extension requires the same privileges that would be required to create its component objects\&. For most extensions this means superuser or database owner privileges are needed\&. The user who runs
CREATE EXTENSION
becomes the owner of the extension for purposes of later privilege checks, as well as the owner of any objects created by the extension\*(Aqs script\&.
.SH "PARAMETERS"
.PP
IF NOT EXISTS
.RS 4
Do not throw an error if an extension with the same name already exists\&. A notice is issued in this case\&. Note that there is no guarantee that the existing extension is anything like the one that would have been created from the currently\-available script file\&.
.RE
.PP
\fIextension_name\fR
.RS 4
The name of the extension to be installed\&.
PostgreSQL
will create the extension using details from the file
SHAREDIR/extension/\fIextension_name\fR\&.control\&.
.RE
.PP
\fIschema\fR
.RS 4
The name of the schema in which to install the extension\*(Aqs objects, given that the extension allows its contents to be relocated\&. The named schema must already exist\&. If not specified, and the extension\*(Aqs control file does not specify a schema either, the current default object creation schema is used\&.
.RE
.PP
\fIversion\fR
.RS 4
The version of the extension to install\&. This can be written as either an identifier or a string literal\&. The default version is whatever is specified in the extension\*(Aqs control file\&.
.RE
.PP
\fIold_version\fR
.RS 4
FROM
\fIold_version\fR
must be specified when, and only when, you are attempting to install an extension that replaces an
\(lqold style\(rq
module that is just a collection of objects not packaged into an extension\&. This option causes
CREATE EXTENSION
to run an alternative installation script that absorbs the existing objects into the extension, instead of creating new objects\&. Be careful that
SCHEMA
specifies the schema containing these pre\-existing objects\&.
.sp
The value to use for
\fIold_version\fR
is determined by the extension\*(Aqs author, and might vary if there is more than one version of the old\-style module that can be upgraded into an extension\&. For the standard additional modules supplied with pre\-9\&.1
PostgreSQL, use
unpackaged
for
\fIold_version\fR
when updating a module to extension style\&.
.RE
.SH "NOTES"
.PP
Before you can use
CREATE EXTENSION
to load an extension into a database, the extension\*(Aqs supporting files must be installed\&. Information about installing the extensions supplied with
PostgreSQL
can be found in
Additional Supplied Modules\&.
.PP
The extensions currently available for loading can be identified from the
pg_available_extensions
or
pg_available_extension_versions
system views\&.
.PP
For information about writing new extensions, see
Section 35.15, \(lqPackaging Related Objects into an Extension\(rq, in the documentation\&.
.SH "EXAMPLES"
.PP
Install the
hstore
extension into the current database:
.sp
.if n \{\
.RS 4
.\}
.nf
CREATE EXTENSION hstore;
.fi
.if n \{\
.RE
.\}
.PP
Update a pre\-9\&.1 installation of
hstore
into extension style:
.sp
.if n \{\
.RS 4
.\}
.nf
CREATE EXTENSION hstore SCHEMA public FROM unpackaged;
.fi
.if n \{\
.RE
.\}
.sp
Be careful to specify the schema in which you installed the existing
hstore
objects\&.
.SH "COMPATIBILITY"
.PP

CREATE EXTENSION
is a
PostgreSQL
extension\&.
.SH "SEE ALSO"
ALTER EXTENSION (\fBALTER_EXTENSION\fR(7)), DROP EXTENSION (\fBDROP_EXTENSION\fR(7))
